The Institute of Electrical and Electronics Engineers (IEEE) standards 802.3-based access networks (also referred to as Ethernet) can be classified generally into two major groups, i.e., shared media (referred to as point-to-multipoint (P2MP)) and dedicated media access (referred to as point-to-point (P2P)). P2P access networks are typically implemented over a duplex fiber (a fiber pair), with each fiber carrying optical signals in only one direction (from a hub to a customer premise, i.e., downstream, or from the customer premise to the hub, i.e., upstream). P2MP access networks (typically Passive Optical Network (PON)) are typically implemented over a simplex fiber (a single fiber), carrying optical signals in both upstream and downstream directions multiplexed into a single fiber using Wavelength Division Multiplexing (WDM) technology.
Along with the push for deeper fiber deployment in the access networks, a fiber strand is becoming a very expensive commodity and using a duplex fiber (pair of fibers) per customer in P2P access is becoming prohibitively expensive, especially when considering that a simple change in the signal multiplexing cuts down the number of required fibers per customer by half. The use of wavelength division multiplexing (WDM) for P2P access to drive the use of simplex fiber rather than duplex fiber was the premise for development of a class of simplex P2P access technologies under the so-called Ethernet in the First Mile (EFM) project in IEEE 802.3, providing 100 Mb/s and 1000 Mb/s access speeds. A new project (http://www.ieee802.org/3/NGBIDI/index.html) in IEEE 802.3 Working Group aims to provide simplex P2P access technologies for 10 Gb/s, 25 Gb/s, and 50 Gb/s speeds, while preserving the use of a single fiber in the access portion of the telecommunication network.
Along with the use of a simple fiber comes a problem. In the past, when P2P and P2MP used different numbers of fibers, there was no way for a field technician to make a mistake and connect a P2P Customer Premise Equipment (CPE) to a P2MP network or vice versa. Such CPE incompatibility was guaranteed using different fiber connectors, i.e., a dual Lucent Connector (LC) for P2P CPE and a single standard or subscriber connector (SC) for P2MP CPE. With the move of P2P access networks to simplex fiber comes also the move to the SC connector, i.e., currently both P2P and P2MP CPEs utilize the very same type of fiber connector, i.e., a single SC connector. This means that there is now a non-zero chance that a wrong CPE type is connected to a wrong network type, i.e., a P2P CPE is connected to a P2MP network or vice versa. For example, when a P2P CPE is connected to a P2MP network, such a device by default immediately starts transmitting in the upstream direction, effectively preventing the proper operation in the Time Division Multiplexing (TDM)-based upstream direction in a P2MP access network. In such a simple manner, one wrong P2P CPE connected to a P2MP network can take down a whole P2MP network and prevent any user from accessing the network resources.